Apollo: News

[Len]

"Recently we implemented source flags inside a torrent file such that torrents downloaded from APL would have a unique info hash compared to other sites.

This only affects newly uploaded torrents. Torrents uploaded before this implementation will not have the source flag.

What?

The BitTorrent Specification states that inside every .torrent file there's a dictionary of keys/values "info" that contains at least the following keys:

piece length
pieces
name
files: a list of dictionaries, one for each file.


and optionally:

private (which exists in all torrent files downloaded from private trackers)


From all of the keys and values of the info dictionary, an "info_hash" is generated that is unique per torrent. A torrent client only allows one torrent per info_hash. If you upload a torrent file to two different sites that don't change the torrent files at all and then someone downloads them, their client will only add it once and will insist on adding the announce URLs for the sites into one torrent file. While this is fine for public torrent sites, this doesn't work on private trackers, where the announce URLs must only point to one site. This makes cross-seeding (if we only use the minimal set of keys allowed for "info") between multiple private tracker sites cumbersome for both uploaders and downloaders.

Source Flag?

To make cross-seeding easier, people have started inserting additional keys into the "info" dictionary that can be used to make the torrent's info_hash unique per site allowing multiple torrent files that were otherwise the same co-exist within clients. For example, whatbox adds a "unique" key and PyroCore adds "x_cross_seed". Many private trackers have started to center around using the "source" key/flag, generally setting to the site's initials (so for us it's APL). The source flag can then either be set on torrent creation or on upload to the site, like the private key/flag. Unfortunately, when the flag is created by the site on upload, the new torrent file must be downloaded by the user and added to their client, with their original torrent that they uploaded being rendered useless.

How can I set it in my client?

Unfortunately, unlike private which is part of the official BitTorrent specification, source is an informal flag that many private trackers have rallied behind using, and as such isn't available to set within most clients on torrent creation. We suggest that users use mktorrent or dottorrent-guii which does allow setting the source flag to "APL" when creating the torrent file, which means that you won't need to re-download the torrent file after uploading. mktorrent for example has a "-s" or "--source" flags that you can use to set the source flag to "APL". dottorrent-gui has it built in at the bottom of the form:
Image: Show

If you want to continue using uTorrent, Deluge, Transmission or any other client for creating the torrent files, this is no problem. However, when you upload a torrent without source flag, the site will give you an error, telling you to re-download the torrent. To start seeding, you should go to the torrent page of the torrent you just uploaded, download the torrent, and load it into your client of choice. (you might need to point your client to the correct location of the files, and do a recheck before the client recognizes the torrent as being 100% completed and starts seeding.)"